class MyCircularQueue {
    //留一个空间表示满
    private int[] elem;
    private int front;//队头下标
    private int rear;//队尾下标

    //实例化一个循环数组
    public MyCircularQueue(int k) {
        this.elem = new int[k];
    }

    //入队
    public boolean enQueue(int value) {
        if(isFull()) {
            return false;
        }
        elem[rear] = value;
        rear = (rear + 1) % elem.length;
        return true;
    }

    //出队
    public boolean deQueue() {
        if(isEmpty()) {
            return false;
        }
        front = (front + 1) % elem.length;
        return true;
    }

    //得到队头元素
    public int Front() {
        if(isEmpty()) {
            return -1;
        }
        return elem[front];
    }

    //得到队尾元素
    public int Rear() {
        return (rear == 0) ? elem.length - 1 : rear + 1;
    }
    
    public boolean isEmpty() {
        if(rear == front) {
            return true;
        }
        return false;
    }
    
    public boolean isFull() {
        //(rear + 1) % elem.length == front 相等就表示改队列满了
        if((rear + 1) % elem.length == front) {
            return true;
        }
        return false;
    }

    public static void main(String[] args) {
        MyCircularQueue myCircularQueue = new MyCircularQueue(3);
        myCircularQueue.enQueue(1);
        myCircularQueue.enQueue(2);
        myCircularQueue.enQueue(3);
        myCircularQueue.enQueue(4);
        System.out.println(myCircularQueue.Rear());
        System.out.println(myCircularQueue.isFull());
        System.out.println(myCircularQueue.deQueue());
        myCircularQueue.enQueue(4);
        System.out.println(myCircularQueue.Rear());
    }
}